Induction heated pipe



Nov. 7, 1939. c. E. DANIELS INDUCTION HEATED PIPE Filed Feb. 25, 1938 I INVENTOR. Charles Ellaniela ATTORN EY- Patented Nov. 7, 1939 I YVUVNITED STATES PATENT OFFICE INDUCTION HEATED PIPE Application February 23, 1938, Serial No. 192,142

' 6 Claims. (Cl. 219-47) This invention relates to electrically heated pipes, conduits and process lines. More particularly it relates to an induction heated non-magnetic pipe or conduit construction. Still more particularly it relates to an insulated non-magnetic pipe or conduit construction which is pro-- vided with means for heating the same by electrical induction.

It is an object of this invention to provide an eflicient means of heating a non-magnetic pipe, conduit or process line. A further object is to provide a pipe line construction capable of being maintained at a uniform elevated temperature. A still further object is to provide a pipe or conduit construction which is simple in design, electrically heated, and requires no replacement of parts.

The ordinary methods of heating process lines such as those used in the chemical and related industries comprise jacketing them with a high temperature heating medium, electrical heating utilizing container resistance or resistor elements, or by direct fire of combustible materials. Each of these methods has distinct disadvantages which definitely limit its usefulness. For instance, electrical resistor heaters localize the application of their heat and require frequent replacement while direct fire heating is bulky, ineflicient due to' heat losses from radiation, and convection, and entails a constant fire hazard.

The above objects are accomplished free from .the disadvantages mentioned, by the following invention, which comprises a novel pipe conduit or process l ne construction. The novel construction comprises a pipe composed of non-magnetic material such as copper, brass, aluminum, etc. which has a plurality of 'magnetic elements disposed about the periphery or exterior surface of in similar reference numerals refer to similar parts throughout the several views.

Fig. 1 is a side elevation of a pipe section with certain parts shown in section.

Fig. 2 is a cross-section taken along 2-2 of Fig. 1.

Fig. 3 is a cross-section taken through the pipe showing a modified type of magnetic element.

Fig. 4 is a cross-section taken through the 5 pipe showing a modified type of magnetic element.

Fig. 5 is a cross-section taken through the pipe showing a modified type of magnetic element.

. In the drawing the non-magnetic pipes or con- 0 duit I has disposed about its periphery a series of elements 2 which'are relatively small in crosssection and of appreciable length and are composed of magnetic material such as iron. The elements may be round, square, flat, polygonal, angular or channel-shaped in cross-section and are maintained in a fixed position to the line by a bolted clamp 3. The rods, etc. are preferably uniformly spaced about the exterior surface of the pipe or conduit. Totally surrounding the rods and clamping means is the heat insulating material 4, about which is coiled the electrical the lines wire windings 5 which is connected to any suitable alternating current supply.

The electrical current fiowing in the wire coils 5 sets up flux lines in the magnetic rods 2' inducing therein electrical currents which are dissipated as heat. Due to the actual contact and enclosed association of the rods 2 with the process line or pipe I, the heat generated is rapidly transferred to the process line. Actual tests have shown that the temperature difference between the rods and line may be reduced to a negligible amount. 4

. The total cross-sectional area of the magnetic 36 rods as compared with the cross-sectional area of the pipe may vary widely, depending upon the materials to be conveyed and the temperatures desired to be maintained. The total cross-sectional area of the magnetic rods preferably should 40 at least be equal to the cross-sectional area of the walls of a standard iron pipe having the same internal diameter as the non-magnetic pipe such as a copper pipe. The magnetic rods are preferably straight but may be sinuous or otherwise irregular in shape. The magnetic rods may furthermore be clad with anon-magnetic heat conducting coating.

I have found that a copper pipe assembled as above described with round rods having a total area equal to the wall area of an iron pipe of the same size can be eflectively maintained at an elevated temperature of 150 to 400 C. for example. Using a wire having 10 turns per foot of pipe when connected to a 110 volt and am- 55 pere supply, temperatures in the neighborhood of 275 to 325 may be easily maintained.

In general with two inch pipe, 600 to 700 turns are used per feet of pipe length at volts and '70 amperes. For feet of pipe two circuits or a higher voltage would be used.

In a compending application, filed upon an even date herewith, entitled "Induction heated fixtures, I have disclosed a removable fixture in an induction-heated magnetic pipe line, the heating coils whereof being arranged so as to maintain the removable fixture at substantially the same temperature as the rest of the line. The fixtures may be similarly mounted in an non-magnetic pipe line of the type set forth above, by increasing the ampere turns adjacent to opposite sides of the fixtures.

While the forms of invention herein disclosed constitute a preferred form hereof, it is to be understood that other forms might be adopted without departing from the spirit of the invention which is to be limited only by the scope of the appended claims. I

I claim:

1. A pipe construction comprising a tubular core of non-magnetic material, a plurality of iongitudinally disposed flux carrying elements disposed about the core in thermal relation therewith, insulation disposed about said members and core and an induction heating coil arranged about said insulation.

2. A tubular core for conveying fluids composed of non-magnetic material, a plurality of spaced rods composed oi! magnetic material longitudinally disposed about and in thermal relationship with the exterior of said core, insulation disposed about said members and core, and an alternating current coil disposed about said insulation.

3. A pipe construction comprising a tubular core of non-magnetic material, aplurality of longitudinally disposed flux carrying elements of relatively small cross-section and appreciable length spaced equally about the core in thermal relation therewith, a layer of insulating material disposed about said members and core, and an induction-heating coil wound about said layer.

4. A pipe construction comprising a tubular core of non-magnetic material, a plurality of rodlike magnetic elements spaced equally about the core in thermal relation therewith, a layer of insulatingmaterial disposed about said members and core, and an induction-heating coil wound about said layer.

5. A pipe construction comprising a lerigjthjo'f pipe composed of non-magnetic metaLa plurality of rod-like magnetic elements spaced "equally around the pipe and extending the length "of the CHARLES E. DANIELS. 

